This invention relates to a personal watercraft and more particularly to an improved direct injected engine therefore that includes an air fuel injector.
In order to improve the efficiency and exhaust emission control for two cycle engines to permit their continued use in applications where compact, high output engines are required, it has been proposed to employ direct cylinder injection systems. Such systems inject the fuel directly into the combustion chamber of the engine. This permits more efficient control of the amount of fuel introduced as well as the timing thereof to improve engine efficiency.
With two cycle engines, on the other hand, at least a portion of the injection cycle takes place at the same time scavenging is occurring and hence, the fuel must be injected fairly rapidly over a relatively short time period to avoid escape along with the exhaust gasses. This results in high injection pressures that can present problems such as fuel condensation on the walls of the combustion chamber.
It has been well known that in order to improve fuel atomization, air may be injected along with the fuel so as to prevent these problems. This concept was utilized in the earliest internal combustion engines. However, the application of air fuel injectors for such small, compact arrangements such as personal watercraft presents significant problems.
A personal watercraft is a well known type of watercraft which may assume many forms. However, a common characteristic of all personal watercraft is that they are designed to be operated by a single rider who may carry no more than two or three additional passengers with him. Also, these watercraft are quite compact and sporting in nature. Frequently, the operator and his passengers are seated in straddled, tandem fashion on a single seat that overlies, in part, the engine compartment.
Thus, the engine is positioned in a quite confined location. This is one reason why two cycle engines are desirable for such application. However, where added components such as the components necessitated by a fuel, air injector are incorporated, then the positioning of the components, their serviceability and other factors, which will be mentioned, become quite significant.
It is important that the air that is used with the injection system is compressed to a high enough pressure. Therefore, it is common to use positive displacement pumps for this purpose. However, regardless of the type of air compressor employed, this gives rise to fairly high temperatures. Thus it is important that the compressed air is not heated so highly that it looses its effectiveness.
It is, therefore, a principal object of this invention to provide an improved fuel air injector system for a personal watercraft wherein the air for the compressor and the compressor systems are such that the compressor will be well cooled.
Also, because of the sporting nature of these watercraft, there is a danger that water may enter the air injection system. This can happen due to the fact these watercraft frequently become inverted and subsequently righted. If the air system is such that it becomes immersed in water during this inversion and righting process, then damage can result.
It is, therefore, a still further object of this invention to provide an improved air compressor arrangement for a personal watercraft wherein the compressor and its components are protected from the water.